Well considering that three of the four characters (all the girls) were themselves guilty of beleiving the nonsense spouted about Harry in the second, fourth and fifth years (except perhaps Susan Bones), it's trifle rich to hear all the indictment of Hogwarts professors coming from them.
Why don't I recall the brave Gryffindor Parvati Patil stand up for her housemate Harry in those times? Strangely enough she had nothing adverse to say against her favourite teacher Sybil Trelawney whose lessons were a bigger hocum than those of Binns if not anything else.
The icy Slytherin never gave any indication that she ever stood on the good side.
The shy Hufflepuff was hardly volunteering to shush Ernie McMillan or her housemates when Harry was being labelled a dark lord, heir of Slytherin, an attention seeking prat, a liar and what not.
And they have the gall to take moral high ground against bullying, when having either actively participated or at least condoned the same during their times at Hogwarts.
The only one with any ground to stand on here would be Neville Longbottom.